The storage of materials in tanks or vessels at temperatures above or below ambient temperature requires the use of insulation. Often the tanks or vessels are double walled with insulation filling the space between the inner and outer walls. The insulation used is often granular, such as perlite, but to avoid creating voids when the cavity or space between the walls is filled with insulation it is common to vibrate the outer wall. Vibrating the wall also helps to compact the insulation so that less settling occurs later.
Mendius U.S. Pat. No. 3,633,878 discloses vibrating apparatus for settling insulation in an insulated tank. The vibrator apparatus disclosed in the Mendius patent is removably attached to a tank wall by permanent magnets, electromagnets or vacuum means. Each embodiment has the impact plate pressed into engagement with the tank wall in vibration transmitting relationship. This causes damage to a painted surface being vibrated and also results in the apparatus walking or moving along the surface as vibrating proceeds thereby widening the damaged painted area and directing the vibrating away from the desired area. Furthermore, it is difficult to land a vacuum attachable apparatus, as shown in FIG. 5 of the Mendius patent, on a tank wall high above ground with enough contact to readily produce a vacuum.